Re: [PATCH] mm,hwpoison: return -EBUSY when page already poisoned

[David Hildenbrand]

On 31.03.21 12:56, Aili Yao wrote:
> On Thu, 25 Feb 2021 12:39:30 +0100
> Oscar Salvador <osalvador@xxxxxxx> wrote:
>
> > On Thu, Feb 25, 2021 at 11:28:18AM +0000, HORIGUCHI NAOYA(堀口 直也) wrote:
> > > Hi Aili,
> > >
> > > I agree that this set_mce_nospec() is not expected to be called for
> > > "already hwpoisoned" page because in the reported case the error
> > > page is already contained and no need to resort changing cache mode.
> >
> > Out of curiosity, what is the current behavour now?
> > Say we have an ongoing MCE which has marked the page as HWPoison but
> > memory_failure did not take any action on the page yet.
> > And then, we have another MCE, which ends up there.
> > set_mce_nospec might clear _PAGE_PRESENT bit.
> >
> > Does that have any impact on the first MCE?
> >
> > > It seems to me that memory_failure() does not return MF_XXX.  But yes,
> > > returning some positive value for the reported case could be a solution.
> >
> > No, you are right. I somehow managed to confuse myself.
> > I see now that MF_XXX return codes are filtered out in page_action.
> >
> > > We could use some negative value (error code) to report the reported case,
> > > then as you mentioned above, some callers need change to handle the
> > > new case, and the same is true if you use some positive value.
> > > My preference is -EHWPOISON, but other options are fine if justified well.
> >
> > -EHWPOISON seems like a good fit.
>
> Hi Oscar, david:
>
> Long away fron this topic, but i noticed today I made a stupid mistake that EHWPOISON is already
> been declared, so we should better return EHWPOISON for this case.
>
> Really sorry for this!
>
> As the patch is still under review, I will post a new version for this, if I change this, may I add
> your review tag here please?

Just resend as v2. We will review and post our RBs there.


--
Thanks,

David / dhildenb